Tuesday, January 20, 1998 Published at 19:51 GMTUKPlug pulled on historic aqueductThe Pontcysyllte Aqueduct carries the Llangollen canal over the River Dee

Engineers have literally pulled the plug on one of Britain's most famous aqueducts.

Engineers have to refurbish the structure

The 1,000 foot long Pontcysyllte Aqueduct in north Wales was built by Thomas Telford between 1795 and 1805, the year Nelson won the Battle of Trafalgar.

But now the elegant structure is in urgent need of restoration work and the only way engineers could inspect it was by emptying out the water.

Spectators watch the water drain out

At midday on Tuesday, they pulled the plug and 1.5 million litres of water, enough to fill 8,000 baths, cascaded to the River Dee below.

The aqueduct, described by the novelist Sir Walter Scott, as the finest work of art he had ever seen, carries the Llangollen Canal canal on 19 slender arches 120 feet above the Dee Valley.

It is a grade one listed building and there has been talk of it being listed as a UNESCO World Heritage site.

A grade one listed building

British Waterways is spending £25 million in a winter maintenance programme on the aqueduct and other sections of the 2,000 mile canal network.

The draining operation, watched by a large crowd of onlookers, took little more than an hour.

After making sure no stray fish were trapped, workmen eased the plug from the bed of the aqueduct and the hidden secrets of the its construction were then slowly revealed.

The aqueduct took an hour to empty

Telford used a cast-iron channel nine feet wide to carry the water, an innovative feat later described as "a piece of work that would have done credit to the Romans."

Phil Parker, a member of the British Waterways engineering team, said: "The aqueduct is now 200 years old and needs a little tender loving care. It is an absolutely stunning piece of civil engineering.

"We shall be checking that all the joints are watertight and doing some maintenance on the towpath and handrailing along its length."